leastsignificant

Least significant is a term used in mathematics and computer science to describe the part of a number that contributes the smallest amount to its value. In positional numeral systems, the least significant digit is the rightmost digit; in binary, the least significant bit is the rightmost bit and has weight 2^0. Conversely, the most significant part has the largest weight. The concept applies to integers, fixed-point numbers, and digital data.

In computing, the distinction between least and most significant influences data representation and operations. Endianness refers to the order in which bytes are stored or transmitted; in little-endian systems, the least significant byte is stored first, while big-endian systems store the most significant byte first. Within a byte, bit significance is independent of endianness, with the least significant bit still representing the least power of two. Right-to-left processing and masking often focus on the least significant bits or digits.

Applications include arithmetic, error detection, and data encoding. Bit tricks use the least significant bit to test parity, isolate the least significant 1 bit, or count trailing zeros. In decimal notation, the least significant digit is the units place, affecting rounding and modular arithmetic. In practice, software may shift or mask toward the least significant side to perform efficient low-level operations or to extract low-order information from a value. See also most significant bit, endianness, and bitwise operations.